package chapter20;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Created with IntelliJ IDEA.
 * Description:
 *
 * @author liuziyang
 * @create 2019-04-04 19:55
 */
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Constraints {
    boolean primaryKey() default false;

    boolean allowNull() default false;

    boolean unique() default false;
}
